Ink jet head for ejecting ink by exerting pressure on ink in ink channels

Abstract

An ink jet head has nozzles and ink channels connected to the nozzles. Side walls of the ink channel are formed from a piezoelectric material, and vary the capacity of the ink channel to eject ink through the nozzle. The ink channels each have a flat bottom surface at a site apart from the site of connection with the nozzle, and the ratio of H2, the depth of the ink channel at the site of connection with the nozzle, to H1, the depth of the ink channel having the flat bottom surface, i.e., the ratio H2/H1, is in the range of from 0.1 to 0.8. The ratio of the distance between the side walls of the ink channel to the height of the side wall of the ink channel at the site of connection with the nozzle is in the range of from 0.5 to 2.0. Thus, air bubbles building up in the ink channel can be easily discharged.

What is claimed is: 
     
       1. An ink jet head, comprising: at least one nozzle formed at one end of the ink jet head; and   at least one ink channel formed inside the ink jet head so as to connect with the at least one nozzle, an ink channel connected to a nozzle; wherein   the at least one ink channel is formed so as to have a flat bottom surface at a portion apart from a portion connected to the at least one nozzle and such that a ratio H2/H1 of a depth H2 of the at least one ink channel at the portion connected to the at least one nozzle to a depth H1 of the at least one ink channel having the flat bottom surface is in a range of from 0.1 to 0.8.   
     
     
       2. The ink jet head as claimed in claim 1, including: a head body having the at least one ink channel formed so as to pass through the inside of the head body, and a nozzle plate having the at least one nozzle formed therein; wherein   the nozzle plate is secured to the head body such that the at least one nozzle is connected to one open end of the head body formed by the at least one ink channel passing through the inside of the head body.   
     
     
       3. The ink jet head as claimed in claim 2, wherein the at least one ink channel passes straight through the head body. 
     
     
       4. The ink jet head as claimed in claim 2, wherein the depth H2 is the depth of the at least one ink channel at the one open end, while the depth H1 is the depth of the at least one ink channel at another open end, and the depth of the ink channel gradually decreases, beginning at an ink channel portion having the flat bottom surface and ending at the portion connected to the at least one nozzle. 
     
     
       5. The ink jet head as claimed in claim 1, wherein the at least one ink channel is formed such that the ratio H2/H1 of the depth H2 to the depth H1 is in the range of from 0.2 to 0.6. 
     
     
       6. The ink jet head as claimed in claim 1, having a plurality of side walls wherein each of the side walls of the at least one ink channel can be deformed so as to vary the cross-sectional area of the at least one ink channel, whereby ink in the at least one ink channel is ejected through the at least one nozzle. 
     
     
       7. The ink jet head as claimed in claim 6, wherein the side wall of the at least one ink channel is composed of a piezoelectric material, and a drive electrode for deforming the piezoelectric material is provided on the side wall. 
     
     
       8. The ink jet head as claimed in claim 6, wherein the side wall of the at least one ink channel is composed of an upper portion and a lower portion, and the upper portion and the lower portion are made of piezoelectric materials polarized in different directions of polarization. 
     
     
       9. The ink jet head as claimed in claim 1, wherein a ratio of a distance between side walls of the at least one ink channel to a height of the side walls of the at least one ink channel at a portion connected to the at least one nozzle is in a range of from 0.5 to 2.0. 
     
     
       10. An ink jet head, comprising: at least one nozzle formed at one end of the ink jet head; and   at least one ink channel formed inside the ink jet head so as to connect with the at least one nozzle, an ink channel connected to a nozzle, wherein   a ratio of a distance between side walls of the at least one ink channel to a height of the side walls of the at least one ink channel at a portion connected to the at least one nozzle is in a range of from 0.5 to 2.0; and   wherein a cross sectional area of the at least one ink channel is larger at an inward site of the head than at a site of connection with the at least one nozzle.   
     
     
       11. The inkjet head as claimed in claim 10, including: a head body having the at least one ink channel formed so as to pass through the inside of the head body, and a nozzle plate having at least one nozzle formed therein; wherein   the nozzle plate is secured to the head body such that the at least one nozzle is connected to one open end of the head body formed by the at least one ink channel passing through the inside of the head body.   
     
     
       12. The ink jet head as claimed in claim 11, wherein the at least one ink channel passes straight through the head body. 
     
     
       13. The ink jet head as claimed in claim 11, wherein the at least one ink channel is formed so as to have a flat bottom surface at a portion apart from the portion connected to the at least one nozzle and such that a ratio H2/H1 of a depth H2 of the at least one ink channel at the portion connected to the at least one nozzle to the depth H1 of the at least one ink channel having the flat bottom surface is in a range of from 0.1 to 0.8. 
     
     
       14. The ink jet head as claimed in claim 13, wherein the at least one ink channel is formed such that the ratio H2/H1 of the depth H2 to the depth H1 is in the range of from 0.2 to 0.6. 
     
     
       15. The ink jet head as claimed in claim 10, wherein the side walls of the ink channel can be deformed so as to vary a cross-sectional area of the at least one ink channel, whereby ink in the at least one ink channel is ejected through the at least one nozzle. 
     
     
       16. The ink jet head as claimed in claim 15, wherein the side walls of the at least one ink channel are composed of a piezoelectric material, and a drive electrode for deforming each piezoelectric material is provided on the side wall. 
     
     
       17. The ink jet head as claimed in claim 15, wherein the side walls of the at least one ink channel are composed of an upper portion and a lower portion, and the upper portion and the lower portion are made of piezoelectric materials polarized in different directions of polarization. 
     
     
       18. An ink jet recorder, comprising: an ink jet head having at least one nozzle formed at one end of the ink jet head, and at least one ink channel formed inside the ink jet head so as to connect with the at least one nozzle; and   an ink supply device for supplying ink to the ink jet head, wherein the at least one ink channel is formed so as to have a flat bottom surface at a portion apart from a portion connected to the at least one nozzle and such that a ratio H2/H1 of a depth H2 of the at least one ink channel at the portion connected to the at least one nozzle to a depth H1 of the at least one ink channel having the flat bottom surface is in a range of from 0.1 to 0.8.     
     
     
       19. An ink jet recorder, comprising: an ink jet head having at least one nozzle formed at one end of the ink jet head, and at least one ink channel formed inside the ink jet head so as to connect with the at least one nozzle; and   an ink supply device for supplying ink to the ink jet head, wherein   a ratio of a distance between side walls of the at least one ink channel to a height of the side walls of the at least one ink channel at a portion connected to the at least one nozzle is in a range of from 0.5 to 2.0; and   wherein a cross sectional area of the at least one ink channel is larger at an inward site of the head than at a site of connection with the at least one nozzle.   
     
     
       20. The ink jet recorder as claimed in claim 19, wherein the at least one ink channel is formed so as to have a flat bottom surface at a portion apart from a portion connected to the at least one nozzle and such that a ratio H2/H1 of a depth H2 of the at least one ink channel at the portion connected to the at least one nozzle to a depth H1 of the at least one ink channel having the flat bottom surface is in a range of from 0.1 to 0.8.